Re: [Gnu-arch-users] [PATCH] arch speedups on big trees

[Aaron Bentley]

On Wed, 2004-01-28 at 14:20, Chris Mason wrote:

> > add-pristine can, indeed, take a --link option.
> > 
> Since libraries can be linked, and libraries would eventually kill
> pristine trees, there's no need to add code to pristine trees that you
> would just kill later on.

If doing after the fact is useful to you, tla changes --link will
hardlink to a pristine just as well as it does to a revlib.


> I'm sure there are better ways to make it faster than my current code,
> but I haven't seen a lot of other ideas discussed.

I think that hinting combined with with partial tree inventories can
provide similar performance to reverse mapping.  Maybe I wasn't clear in
that post, or maybe there are flaws I don't see:

If you've got hints and partial tree inventories (i.e. "search the tree
for these ids, and start with these files"), performance should be
similar to your original patch, but entirely safe.

For inexact patching:

To handle the case where a file is renamed, but remains in the same
directory, you can hint all the files in the same directory as altered
files.  You'd put them lower in the list than the entries for the actual
altered files, so you'd only search them if the files *had* been
renamed.

For a totally random file move, you'll do a half-tree inventory, on
average.  But there are probably other forms of hinting that can reduce
that too.  Like hinting directories/files with recent mtimes.

Does that make sense?

Aaron
-- 
Aaron Bentley
Director of Technology
PanoMetrics, Inc.